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Old 3rd Jun 2004, 23:08
  #20 (permalink)  
Divergent Phugoid!
 
Join Date: Aug 2002
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Spotter.....

A divergent phugoid is a way of assessing the long period longitudinal instability of an aircraft. The aircraft is set up and trimmed in straight and level flight and the control column is pushed / pulled to upset the pitch stability of the aircraft. The length of time taken to recover to straight and level flight (and the number of pitch oscillations) is a measure of the stability of the aircraft and the graph of the pitch characteristics of the aircraft describes a phugoid. A divergent phugoid is one where there is negative stability and the amplitude of the pitch oscillations increases.

The closest equivalent analogy I can think of is the shock absorbers on your car - if you depress one corner of the car, the correct response (assuming good shock absorbers) is a decaying sinusoidal pitch oscillation.

Another similie is a Tank slapper on a bike!

Good luck with the course, but dont tell anyone you're going!
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